Next to clean water, phosphorus will be one the inexorable limits to human occupancy on this planet” wrote Bill Mollison in Permaculture: A Designers’ Manual more than 20 years ago .

Peak Phosphorus barely registers alongside it’s more gregarious, attention-getting bigger brother, Peak Oil. Yet, the implications are even more dramatic. While both peaks are associated with massive food shortages, unmitigated Peak Phosphorus would easily win the award for best disaster.

The latest research tells us that Peak Phosphorus is an issue we cannot afford to ignore any more:

… a global production peak of phosphate rock is estimated to occur around 2033. While this may seem in the distant future, there are currently no alternatives on the market today that could replace phosphate rock on any significant scale. New infrastructure and institutional arrangements required could take decades to develop.

While all the world’s farmers require access to phosphorus fertilizers, the major phosphate rock reserves are under the control of a small number of countries including China, Morocco and the US. China recently imposed a 135% export tariff on phosphate rock essentially preventing any from leaving the country. Reserves in the U.S. are calculated to be depleted within 30 years. Morocco currently occupies Western Sahara and its massive phosphate rock reserves, contrary to UN resolutions. – Western Sahara Resource Watch

Battered by soaring fertiliser prices and rioting rice farmers, the global food industry may also have to deal with a potentially catastrophic future shortage of phosphorus, scientists say.

Researchers in Australia, Europe and the United States have given warning that the element, which is essential to all living things, is at the heart of modern farming and has no synthetic alternative, is being mined, used and wasted as never before.

Massive inefficiencies in the “farm-to-fork” processing of food and the soaring appetite for meat and dairy produce across Asia is stoking demand for phosphorus faster and further than anyone had predicted. “Peak phosphorus”, say scientists, could hit the world in just 30 years. Crop-based biofuels, whose production methods and usage suck phosphorus out of the agricultural system in unprecedented volumes, have, researchers in Brazil say, made the problem many times worse. Already, India is running low on matches as factories run short of phosphorus; the Brazilian Government has spoken of a need to nationalise privately held mines that supply the fertiliser industry and Swedish scientists are busily redesigning toilets to separate and collect urine in an attempt to conserve the precious element.

Dana Cordell, a senior researcher at the Institute for Sustainable Futures at the University of Technology in Sydney, said: “Quite simply, without phosphorus we cannot produce food. At current rates, reserves will be depleted in the next 50 to 100 years.

Human excreta (urine and feces) are renewable and readily available sources of phosphorus.Urine is essentially sterile and contains plant-available nutrients (P,N,K) in the correct ratio.Treatment and reuse is very simple and the World Health Organization has published 'guidelines for the safe use of wastewater, excreta and greywater.

More that 50% of the worlds’ population are now living in urban centers, and in the next 50 years 90% of the new population are expected to reside in urban slums. Urine is the largest single source of P emerging from human settlements.

According to some studies in Sweden and Zimbabwe, the nutrients in one person's urine are sufficient to produce 50-100% of the food requirements for another person. Combined with other organic sources like manure and food waste, the phosphorus value in urine and feces can essentially replace the demand for phosphate rock. In 2000, the global population produced 3 million tonnes of phosphorus from urine and feces alone.